Title: Long-Term Monitoring of Dynamical Motions in the Accretion Disks of AGNs

Abstract:
Our ongoing long-term study of ``disk-like'' emission lines in AGNs
has demonstrated that the accretion disk is indeed the most likely
origin of these double-peaked lines. They must be rather common too,
since they often appear in nearby LINERs. In the course of our study we
have found that most of these double-peaked line profiles vary
dramatically on time scales of months to years. The observed
variability time scale is compatible with the dynamical time in an
accretion disk at several hundred gravitational radii. We are comparing
the observed evolution of the line profiles with detailed models of
dynamical phenomena that are thought to occur in disks. These
applications will provide direct measurements of the black hole mass,
and will evaluate models for tidal disruption of stars, elliptical
accretion rings, spiral waves in accretion disks, and accretion-disk
winds. The full range of profile variability may take decades to
characterize, but for now we make a modest proposal to continue our long-
term monitoring, observing the variable line profiles twice a year for
another six years. It is apparent from a decade's worth of data that
there are specific patterns in the variability of the line profiles.
The most important observational fact that we now need to learn is
whether the observed variations are regular and periodic. The proposed
observing runs at NOAO will contribute approximately half of the
quarterly monitoring intervals that we need to adequately sample the
variability, with other telescopes filling in the rest.